This invention relates to a method and apparatus for analysis of neoplasia in tissue and for pre-invasive cancer and for analysis of the effect of chemopreventive agents with respect to neoplasia.
Currently, there are on-going chemoprevention programs that involve the routine testing of chemopreventive agents with the aims of using such agents to reduce the incidence of cancer by stopping the cancer progression or to regress the cancer. These programs desire to test a very large number of chemopreventive agents which occur naturally in foods or drinks or synthesized drugs for their efficacy. Currently, there are a number of centers that are testing chemopreventive agents and that use pathologists to visually examine tissue and quantify the efficacy of these agents administered to animals or humans. These visual assessments are quite broad and are subjective and usually result in assessments such as nuclear grade, carcinoma in situ, preneoplastic intraepithelial neoplasia, etc. It will be appreciated that the limited ability of the human eye to make visual assessments often requires the neoplasia to reach an advanced state in its evolution before it can be assessed. However, it is preferred to quantitatively evaluate the evolution of neoplasia in its early stage of evolution. The earlier the effective evaluation, the better chance of halting the progression of premalignant cells to the malignant state and the earlier that the effectiveness of possible chemopreventive agents can be determined.
A number of benefits are obtained by an earlier evaluation of the effectiveness of a chemopreventive agent. First, a very substantial cost benefit results from the ability to quantitatively evaluate premalignant tissue if done after an animal or person has been treated for ten to twenty weeks rather than to wait for the current thirty to forty weeks, which is often the case for visual evaluation by a pathologist. Further, if the apparatus and methodology used are more sensitive or precise than those used by the pathologist, fewer subjects need to be tested. This reduces the cost of analysis with respect to a particular chemopreventive agent or subject, and allows for more analyses to be done at any given testing facility in a given time frame. Of course, obvious health benefits accrue from earlier detection of a precancerous condition and the ability to monitor more quickly and more precisely the effectiveness of chemopreventive treatment for a given patient.
An article by Boone and Kelloff, entitled "Development of Surrogate Endpoint Biomarkers for Clinical Trials of Cancer Chemopreventive Agents: Relationships to Fundamental Properties of Preinvasive (Intraepithelial) Neoplasia", describes chemoprevention as the prevention of clinical cancer by the administration of drugs or dietary constituents prior to or during the early phases of precancerous neoplasia, i.e., while the neoplastic process is still confined to the intraepithelial compartment and has not yet become invasive. Boone and Kelloff describe tissue and cell changes and the need for the development of surrogate endpoint biomarkers (SEBs), and divide the evolution of neoplasia as a continuum divided for convenience into five phases. In Phase I, genomic instability is present in an otherwise normal-appearing epithelium. In Phase II, clonal expansion of a mutated cell occurs. The individual cells are normal in appearance but crowded and disorganized in pattern, with compression of the surrounding normal cells. This is the classic benign epithelioma (aberrant crypt foci of the colon are an example). In Phase III, the cells develop abnormal morphology (described in detail below). Phase IV is marked by invasion, the classic criterion by which pathologists make the diagnosis of cancer; and in Phase V, there is wide-spread dissemination. The ideal SEB should detect early changes during the intraepithelial neoplastic period and should monotonically increase in magnitude with neoplastic growth. The present invention is directed to providing a method and apparatus to assay cellular or tissue changes associated with the early neoplastic process, i.e., Stages I, II or III, prior to invasiveness and to be useful for many different tissue types, e.g. breast tissue, colon tissue, prostate tissue, esophageal tissue, skin tissue, cervix tissue, etc. for animals as well as for humans.
One problem with assaying such a variety of tissues is a determination of what measurements or features are most relevant or robust for each given neoplasia in that tissue. The measurements that provide the highest discrimination will vary from one neoplastic tissue to another type of neoplastic tissue. It will be appreciated that the various tissue types described above, such as breast tissue, colon tissue, prostate tissue, esophageal tissue, skin tissue, and cervix tissue have different morphologies, and they undergo different neoplasias usually resulting from a cellular mutation rate as may be enhanced by a carcinogen or resulting from a cellular proliferation rate enhanced by sex hormones, irritant chemicals or inducers from chronic infection. Currently, there are no good objective biomarkers for such diverse neoplasias that can be done using equipment. There is a need to develop highly discriminating tests or measurements. Additionally, the tests or measurements for neoplasia will be done on different types of animals and on humans and at different clinical sites. Further, the measurements are often made when the change in the neoplasia is quite small, such as when the neoplasia is incipient or because sequential tests are performed at close time intervals to ascertain if the progression of neoplasia has been slowed, stopped or regressed. The neoplasias may have distinct appearances as do their respective tissues. To be highly discriminating for such diverse tissues and diverse neoplasias, there is a need for a system which performs highly discriminating measurements for each particular neoplastic tissue. It has been found that some measurements are very discriminating for some tissues neoplasias but not very discriminating for other neoplasias.
Assuming that appropriate discriminating measuring techniques and data are found, there still is a problem of how to grade or report these diverse test results which are so disparate in form. That is, linear measurements, area measurements, density measurements, surface roughness or texture measurements are made in diverse units, scales and magnitudes; and there exists the problem of how to coherently combine these results into a common scale that will be meaningful, easily understood and easily interpreted by pathologists or clinicians. For example, it would be best if the common scale would be valid and useful for evaluating, for example, thirty (30) different agents for skin precancerous tissue, twenty (20) different agents for esophageal precancerous tissue, and fifty (50) precancerous agents for precancerous colon cancer. Thus, there is a need for a system where the results of the measurements are standardized and objective and are easily conveyed to clinicians and others and will provide them with an understanding of a chronology of the effects of small treatment doses of one or more chemopreventive agents on precancerous tissue.